let n = 3

function climbStairs(n){
    if(n < 2){
        return n
    }
    
    let dp = new Array(n + 1).fill(0);
    
    dp[0] = 1; 
    dp[1] = 1; 
    
    for(let i = 2; i <= n; i++){
        dp[i] = dp[i - 1] + dp[i - 2]
    }
    
    return dp[n];
}

let result = climbStairs(6)
console.log(result)